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Ergot

Claviceps purpurea - Köhler–s Medizinal-Pflanzen-185.jpg

Claviceps purpurea

Scientific classification

Kingdom: Fungi

Division: Ascomycota

Class: Sordariomycetes

Order: Hypocreales

Family: Clavicipitaceae

Genus: Claviceps

Species

About 50, including:

Claviceps africana

Claviceps fusiformis

Claviceps paspali

Claviceps purpurea

Claviceps sorghi

Claviceps zizaniae

Ergot or ergot fungi refers to a group of fungi of the genus Claviceps.[1] The most prominent member of this group is Claviceps purpurea ("rye ergot fungus"). This fungus grows on rye and related plants, and produces alkaloids that can cause ergotism in humans and other mammals who consume grains contaminated with its fruiting structure (called ergot sclerotium).[2][3] Claviceps includes about 50 known species, mostly in the tropical regions. Economically significant species include C. purpurea (parasitic on grasses and cereals), C. fusiformis (on pearl millet, buffel grass), C. paspali (on dallis grass), and C. africana[4] (on sorghum). C. purpurea most commonly affects outcrossing species such as rye (its most common host), as well as triticale, wheat and barley. It affects oats only rarely.

C. purpurea has at least three races or varieties, which differ in their host specificity:[5]

G1 — land grasses of open meadows and fields;

G2 — grasses from moist, forest, and mountain habitats;

G3 (C. purpurea var. spartinae) — salt marsh grasses (Spartina, Distichlis).

Contents

1 Life cycle

2 Effects on humans and other mammals

3 History

4 Claviceps purpurea

5 Claviceps africana

6 See also

7 References

8 External links

Life cycle

An ergot kernel, called a sclerotium, develops when a spore of fungal species of the genus Claviceps infects a floret of flowering grass or cereal. The infection process mimics a pollen grain growing into an ovary during fertilization. Infection requires that the fungal spore have access to the stigma; consequently, plants infected by Claviceps are mainly outcrossing species with open flowers, such as rye (Secale cereale) and ryegrasses (genus Lolium). The proliferating fungal mycelium then destroys the plant ovary and connects with the vascular bundle originally intended for seed nutrition. The first stage of ergot infection manifests itself as a white soft tissue (known as sphacelia) producing sugary honeydew, which often drops out of the infected grass florets. This honeydew contains millions of asexual spores (conidia), which